1. Field of the Invention
This invention relates to an optical disc drive for recording and playing back an optical disc and a method of detecting an end portion of recorded data recorded onto an optical disc loaded in the optical disc drive.
2. Description of the Prior Art
There are known optical disc drives for recording and playing back (reproducing) a recordable type optical disc such as a CD-R (CD-Recordable) or CD-RW (CD-Rewritable) or the like.
In such an optical disc drive, there is a case that recording operation is stopped or interrupted during carrying out the operation, because servo control such as a tracking servo control comes to a disengaging or disenabling state due to vibration or the like. In such a case, in order to specify the end portion of the recorded data (a part of EFM data which has been recorded), detection operation is carried out for seeking out the end portion of the recorded data.
However, in the conventional optical disc drives, there is a problem in that it is not possible to detect an end portion of recorded data in each EFM frame (that is, with one EFM frame as a unit for detection).
In the meantime, when the remaining data is to be recorded in a continuous manner or in a followed manner after the end portion of the recorded data, the CD-R standards allow to make overwriting of data up to 12 EFM frames, but the standers do not allow to create a gap (non-recorded portion) between the end portion of the recorded data and the starting portion of the remaining data to be recorded in a continuous manner. Accordingly, if the end portion of the recorded data can not be detected in each EFM frame (that is, with one EFM frame as a unit for detection), there is a case that the overwritten data exceeds 12 EFM frames when the remaining data is recorded. Such an optical disc onto which the remaining data could not be properly recorded in a continuous manner is hard to repair, and therefore it becomes no longer possible to use.
In view of the problem involved in the prior art described above, the object of the present invention is to provide an optical disc drive which can detect an end portion of the recorded data with high precision and a method of detecting the end portion of the recorded data.
In order to achieve the object, the present invention is directed to an optical disc drive for recording and playing back an optical disc, which comprises an optical disc driving mechanism for rotating an optical disc; an optical pick-up for recording and playing back data to and from the optical disc; signal processing means for processing signals read out from the optical disc through the optical pick-up; control means for controlling at least the optical disc driving mechanism, the optical pick-up and the signal processing means, signal generating means for generating a signal of which level changes with one EFM frame as a unit in response to the presence or absence of the recorded data; and means for detecting an end portion of the recorded data recorded onto the optical disc by utilizing the generated signal.
According to the optical disc drive described above, it is possible to detect the end of the recorded data with one EFM frame as a unit. Therefore, even when the recording operation is stopped (that is, when the recording operation is failed), the end portion of the recorded data can be detected with one EFM frame as a unit. With this result, repair of the recording data can be carried out easily, and therefore the remaining non-recorded data can be recorded into the optical disc reliably.
Preferably, the end portion detecting means includes a timer, in which said timer measures a time it takes from a predetermined point of time to a point of time when the level of the signal is changed, and the measured time is converted into the number of EMF frames thereby specifying the EFM frame in which the end portion of the recorded data lies.
In a preferred embodiment, the predetermined point of time is at a time when a SUBCODE-SYBC signal is detected after the optical pick-up has been moved to a subcode frame just preceding to a subcode frame in which the end portion of the recorded data lies and the SUBCODE-SYNC signal has been synchronized with an ATIP-SYNC signal acquired from the disc.
Further, in a preferred embodiment, the level of the generated signal changes in response to the presence or absence of the EFM data recorded onto the optical disc, and the generated signal is a FRAME SYNC signal.
Further, in a preferred embodiment, the optical disc drive further comprises a memory for storing information concerning the end portion of the recorded data.
Another aspect of the present invention is directed to a method of detecting an end portion of data recorded in an optical disc, comprising the steps of: detecting s signal of which level changes with one EFM frame as a unit in response to the presence or absence of the recorded data; and specifying the end portion of the recorded data by utilizing the detected signal.
In this method, it is preferred that a time it takes from a predetermined point of time to a point of time when the signal is detected is measured, and the measured time is converted into the number of EFM frames to specify the EFM frame in which the end portion of the recorded data lies.
In a preferred embodiment of this method, the predetermined point of time is at a time when a SUBCODE-SYBC signal is detected after the optical pick-up has been moved to a subcode frame just preceding to a subcode frame in which the end portion of the recorded data lies and the SUBCODE-SYNC signal has been synchronized with an ATIP-SYNC signal acquired from the disc. Further, the level of the signal changes in response to the presence or absence of the EFM data recorded onto the optical disc. In this method, the signal is a FRAME SYNC signal.